Propeller releasing mechanism



Dec. 16, 1947. c, W, SCOTT 2,432,941

PROPELLER RELEASING MECHANISM Filed Dec. 6, 1941 INVENTOR Car L W 5001:.

. provided Patented Dec. 16, 1947 2,432,941 PROPELLEH RELEASING MECHANISM Carl W. Scott, Ferguson,

Corporation,

Wr' ght ware Mo, assignor to Curtisscorporation of Dela- Application December 6, 1941, Serial No. 421,939 11 Claims. (Cl. 170-477) This invention relates to safety devices for aircraft and is particularly concerned with the release of aircraft propellers during flight.

In certain types of aircraft, particularly those with pusher propellers, e. g., as illustrated in Design Patent No. 111,885 to R. J. Woods, there is great danger that members of the aircraft crew may fall into the path of the propeller blades should it become necessary for them to make an emergency exit from the aircraft cabin during flight. Should some portion of the aircraft fail during flight, the aircraft crew leaves the aircraft for a parachute descent and in leaving. they may become tangled with or injured by the propeller blades.

Thus, it is an object of this invention to provide means by which the aircraft propeller may be released from its driving shaft to fall clear of the aircraft before emergency eXit of the crew.

A further object is to provide a device for locking the propeller upon its shaft during normal operation of the aircraft power plant and to provide in addition. selectively operable means associated with the propeller to sever the driving connection between the shaft and the propeller and to allow the propeller to fall clear of its shaft.

The invention consists essentially of an aircraft assembly including a propeller shaft and a propeller mounted thereon for rotation therewith during normal aircraft flight, said propeller being bodily sheddable in a flight emergency; means for locking said propeller to said shaft during normal aircraft flight; mechanical means operable during propeller rotation and while the aircraft is in flight to release said locking means, said propeller when so released being free'to move along and off an end of said shaft; and a control means (mechanical. electrical, hydraulic or other- Wise) for said mechanical release means operable from within and by an occupant of the space Within the aircraft normally provided for such O ccup ancy.

Further objects of the invention, and a better understanding of the details thereof, will be appreciated in reading the annexed detailed specification in connection with the drawings, in which:

Fig. 1 is a longitudinal section through a tandem propeller hub and shaft assembly incorporating the provisions of the invention; and

Fig. 2 is a section on the line 2-?. of Fig. 1.

A portion of an engine crankcase or other support structure is indicated at Hi, this element having a bushing H in which an outer propeller shaft 12 is journalled, said shaft at its leftward end having a gear l3 driven by suitable means, not shown, from an aircraft engine. The righthand end of the shaft 12 is splined as at M to receive a propeller hub Hi, the hub being maintained in concentric relation with the shaft 12 by centering cones l6 and H, the former abutting a shoulder IS on the shaft l2 and the latter be ing urged leftwardly by a ball thrust bearing l9 embracing an inner propeller shaft 20 journalled at its leftward end in a bushing 21 in the shaft 12. The leftward end of the shaft 20 carries a gear 22 driven by the engine. The rightward end of the shaft 2o comprises splines 24 driving a forward propeller hub 25 which is centered on the shaft 20 by centering cones 26 presses leftwardly against the inner race of the bearing l9. thereby holding the rear propeller iii in place while the righthand cone 21 is pressed leftwardly by a propeller retaining nut designated in its entirety as 28.

The nut 28 comprises a plurality of segments 3i! interiorly threaded to engage the screw threads on the shaft 20, the segments 30 being embraced by a sleeve 32 axially slidable relative to the segrrents but constrained to rotation therewith by keys or splines 34 parallel to the shaft axis and fitted to grooves in the inside of the sleeve 32 and on the outsides of the segments 30. The sleeve 32 includes an end closure 34' having a leftwardly projecting boss 35 and the sleeve and segments are retained in assembled relation by a shear pin 3'6 passing crosswise through them and also through the propeller shaft 12.

Within the propeller shaft 20, whose rightward end is formed as a cylinder, is a piston 38 having a portion 39 abutting the boss 35, the cylinder being defined at its left end by a plug 4B having a tube 4| passing therethrough. The tube ll extends to the left to a suitable spinner bearing 42 connected through a pipe 43 to a cylinder 44 in which is engaged a manually reciprocable plunger 45 operated by a handle 46 through a link 41. The cylinder 44, pipes 41 and 43, and the cylinder within the propeller shaft are filled with hydraulic fluid so that, when the handle 45 is forced to the right, hydraulic pressure built up in the cylinder 44 is transmitted to the propeller shaft cylinder to drive the piston 38 rightwardly, thereby shearing the pin 35 and forcing the sleeve 32 to the right and away from the internally threaded segments 30. Upon removal of the circumferential restraint afforded by the sleeve 32, said segments 30 are free to move radially away from the propeller shaft 20 leaving the propeller 25 with no means for holding it upon for locking the shaft Since in operation there will be substantial aerodynamic drag on the blades of the propellers I and 25, the force occasioned by this cations and changes. I claim as my invention: 1. In aircraft provided with space for an oc- 2. In aircraft provided with space for an ocincluding a means at the outer end of said shaft said propeller to said shaft during emergency normal aircraft flight; mechanical means withn the hollow of said shaft operable during pro- 7 5. In aircraft provided with space for an occupant;

aircraft, the combination of an en propeller drive shaft,

prising internally threaded se ments engaging the shaft threads, a sleeve embracing said segments, and said remotely operable means comprising an axially movable plunger within the embracing said segments, and a shear pin crossshaft engageable with said sleeve to move the wise of the shaft axis normally holding the sleeve latter axially, away from the segments. and segments together.

10. In an aircraft propeller and shaft assem- CARL W. SCOTT. bly for use in an aircraft having space for an cupant, said propeller being keyed to the shaft REFERENCES CITED for rotation therewith but being 8111112111318 there- The following references are f record in t along, screw threads at an end of said shaft, a file of this patent: composite nut engaging said threads and securing the propeller against axial displacement, UNITED STATES PATENTS means remotely operable during propeller oper- Number Name Date ation by said occupant to disassemble said com- 1 7 9 775 Dicks July 1 1930 posite nut from the shaft to allow of axial dis- 1 3 4 71 Doremus June 23 1932 placement of the propeller therealong, said com- 2 257 327 B dford Sept 30, 1941 posite nut comprising internally threaded seg- 1,288,136 Neuteboom Dec. 17,1918 ments engaging the shaft threads, a sleeve em- 2,225,929 Sarazin Dec, 24, 1940 bracing said segments, and a key constraining 1,2 3,301 Pugh A r, 23, 1913 the sleeve and segments against relative rotation. 1,467,537 D m t, 11, 1923 11. In a propeller and shaft assembly, the pro- 1,793,933 Hoffman e 24, 1931 peller being keyed to the shaft for rotation there- 1,431,683 Ramsay Oct. 10, 1922 with but being slidable therealong, screw threads 2,050,283 Dixon Aug, 11, 1936 at an end of said shaft, a composite nut engag- 1,921,893 Steele Aug. 8, 1933 ing said threads and securing the propeller 1,800,094 Muhlenloruck Apr. '7, 1931 against axial displacement, means remotely op- 1,310,330 Farrier July 15, 1919 erable during propeller operation to disassem- 1,672,163 Krammer June 5,1928

ble said composite nut from the shaft to allow of axial displacement of the propeller therealong, FOREIGN PATENTS said composite nut comprising internally thread- Nui'nbcl Country Date ed segments engaging the shaft threads, a sleeve 64,890 Austria Dec. 1, 1913 

